Conventionally, there is a technology called “streaming” for distributing images like moving images and packet data like speech from a media server on the Internet and receiving and playing back the data at a mobile station apparatus. According to this streaming technology, through a radio network connected to the Internet and a base station apparatus connected to the radio network, data such as moving images distributed from a media server is received by a mobile station apparatus from the base station apparatus and the moving images, etc., are played back. The mobile station apparatus that has received packet data such as moving images plays back the data such as the moving images received from the media server.
In such a streaming technology, a phenomenon called “jitter” occurs in which a delay in data reception increases or decreases according to the network condition. When a delay occurs in data reception due to jitter, the data reception rate becomes lower than the data play back rate. In this case, if the received data is continued to be played back, it comes to a point at which there is no more data to be played back and the play back is no longer possible, and therefore the mobile station apparatus is provided with a buffer, the received data is temporarily stored in this buffer, the data is read from the buffer and played back. In this way, even if some delay occurs in received data, the data stored in the buffer is played back and it is thereby possible to prevent play back of data from being stopped due to the delay of the received data. When play back of data is started for the first time, an operation called “buffering” is performed first whereby a predetermined amount of data is stored in the buffer before the data is played back and the received data is stored in the buffer even after play back of data is started and the data to be played back is read from the buffer and played back. The rate at which data is stored in the buffer needs to be set equal to or higher than the rate at which data is read from the buffer to prevent data to be played back from running short during play back.
However, a conventional radio apparatus has a problem that due to deterioration of a communication environment, a maximum transmission rate that can be set up for a communication channel decreases, the data reception rate falls below the rate at which data is read from the buffer making it impossible to play back the data.